Women enduring the pain of labour are not in a position to give informed consent about medical treatments including whether to undergo an epidural, a new study has found.

The use of epidural pain relief on women in labour has doubled in the last two decades

However obtaining true informed consent has always been "difficult", say the authors of a study in the Irish Medical Journal.

The study surveyed 100 mothers at the Coombe Women's Hospital within 24 hours of them giving birth, all of whom had undergone epidural analgesia for labour.

Researchers were trying to determine the information these mothers received prior to getting the epidural and what they would have preferred to have happened regarding consent.

The results showed that mothers' knowledge of potential complications such as prolonged stages of labour and hypotension was "variable and inaccurate".

Less than 30 per cent of women were aware of the most common complications while 79 per cent believed that discomfort during labour affected their ability to provide informed consent.

In all, 96 per cent of the mothers (half of them first-time mums) stated that consent should be taken prior to the onset of labour.

The study also states that 87 per cent believed options for analgesia during labour should be discussed long before they went into hospital to give birth. When asked whether the pain during labour would affect their ability to sign important financial documents a very similar number (81 per cent) believed their decision-making would be compromised.

According to the authors "this raises some difficulties with regard to the consent process for epidural analgesia in labour; an elective symptom-relieving procedure carried out in an otherwise healthy population.

"Informed consent in relation to epidural analgesia is challenging because of the pain associated with the process, the lack of time available for consideration of the risks and the additional influence severe pain may place on a patient requesting epidurals."